The present invention relates to a sealing tool for sealing a package trough with a covering film.
Packages, particularly for foods, are becoming increasingly important today in making foods durable. For packaging, the foods are placed in a so-called package trough and the package trough is then closed gas-tight with a covering film by sealing the covering film onto the edge of the package trough.
As a rule, the package troughs are semi-continuously sealed with a covering film in so-called sealing stations. To this end, the package trough filled with the packaged product and the covering film are initially fed into the sealing station. As soon as the package trough is situated in the sealing station, a first bottom sealing tool is raised vertically from below and pressed against a second, heated top sealing tool located above the covering film. As a result of the pressure and temperature, the covering film and the edge of the package trough, which are situated between the sealing tools, are sealed. In order to obtain a gas-tight seal seam, it is important that the seal seam has a specific width and that the seal seam is essentially situated in the middle of the edge of the package trough. After sealing, the first sealing tool is lowered back beneath the freshly sealed package trough and the sealed package trough is fed on to the cutting station.
Although this type of sealing station has been in operation for several years, it nevertheless displays a number of disadvantages. For instance, package troughs with an undercut cannot be sealed with such a sealing tool because the first sealing tool collides with said undercut during lifting and lowering and destroys it. However, even on packages without an undercut, problems repeatedly occur during the sealing of heavily loaded package troughs because the package troughs sag. Because of this sag, the package troughs turn askew and the first sealing tool on its ascent collides with their corners and destroys or deforms them.